In the chemical, semiconductor and biotechnological industries there are many processes which require real-time analysis and control of a reaction. These processes include gas-phase, liquid-phase, mixed phase and solid-state reactions.
In many cases, there are only indirect and off-line methods used to analyze and control a reaction. There is therefore a need to introduce on-line real-time methods and apparatus for analysis and control of such processes.
Instrumental methods including electrochemical and spectroscopic methods for monitoring wet processing have been reported in the following patents which are considered to be representative of the state of the art:
U.S. Pat. No. 5,097,130 to Koashi, et al. describes a quantitative determination method for processing semiconductors and apparatus thereof. U.S. Pat. No. 6,203,659 to Shen, et al. describes a method and apparatus for controlling the quality of a photoresist stripper bath.
U.S. Pat. No. 6,270,986 to Wong describes a method of preserving biological tissue specimens and method of infrared spectroscopic analysis which avoids the effects of polymorphs.
U.S. Pat. No. 5,893,046 to Wu, et al. describes a real time monitor of reacting chemicals in semiconductors manufacturing. This system requires that one must compare each component with a standard, which does not allow real-time analysis of a multicomponent system. This in situ system in the '046 patent further requires that it be inbuilt in the walls of the bath, in which the solution is contained. This sytsem utilizes a bandpass filter for spectral analysis, which typically gives very poor spectral resolution. It not normally possible to identify each of several bath components with such a device simultaneously. The ability to develop complex algorithms employing the output from the bandpass filter is limited.
There is therefore a need to develop a system for real time analysis of multicomponent systems which overcomes the limitations of this prior art.